An earthquake occurs when built up energy is released from the lithosphere, below the surface of the earth. This energy may be released due to fault line movement or even volcanic activity. The result of this movement is so powerful that it creates seismic waves, which cause the surface of the earth to shake and, sometimes, to fall in. Certain areas around the world are more prone to earthquake activity than others. This propensity to experience an earthquake is known as seismic activity.
How are Earthquakes Measured?
Today, earthquakes are measured by using strong-motion accelerometers, which measure the speed at which the ground moves. When the measurement is complete, the earthquake is assigned a number to indicate its strength. This number may be based on one of several scales, including the Richter scale and the Moment Magnitude scale. The Richter scale is the most widely recognized and measures earthquakes on a scale of 0 to above 8. Anything over a 4 on the Richter scale may begin to cause damage. A 6 or above can cause buildings to collapse and an 8 or above can result in damaged infrastructure, like bridges and roadways.
What is the Most Powerful Earthquake Ever Recorded?
The most powerful earthquake ever recorded occurred on May 22, 1960, near Valdivia, Chile in South America. It is referred to as either the Valdivia Earthquake or the Great Chilean Earthquake. On this day, the shaking began at 3:11 PM local time and lasted for approximately 10 minutes, registering between a 9.4 and a 9.6 on the Moment Magnitude scale. Scientists have determined that this earthquake was so powerful that it represented 25% of all seismic activity around the world between 1906 and 2005.
Just before and slightly after the Valdivia earthquake, Chile experienced a number of earthquakes that are now referred to as the sequence of earthquakes. These disasters began just one day before the Valdivia earthquake in the town of Concepción and lasted until June 6th of the same year. Researchers later identified the Valdivia event as a megathrust earthquake, which takes place at convergent plate boundaries in the subduction zone under the ground. The seismic activity occurs when one tectonic plate is violently pushed under another. This type of earthquake is considered the most powerful and dangerous in the world. This power is the result of higher-than-average energy accumulation within subduction zones. When this energy is released in the form of an earthquake, the result is disastrous.
Areas Affected by the Earthquake
Because the epicenter was located along the Chilean coastline, the strong seismic energy created a tsunami in the ocean and caused waves of up to 82 feet in height in some places. Not only were coastal towns hit by extremely high waves, but the water levels were higher than average and flooding occurred in several places. In Corral, for example, the water throughout the port rose 13 feet higher than usual. Additionally, waves of 33 and 26 feet crashed against the coastal towns between Chiloe Island and Concepción. The resulting tsunami worked its way around the world, traveling across the Pacific Ocean and hitting the shores of the US state of Hawaii, Australia, Japan, the Philippines, and the Aleutian Islands in the US state of Alaska.
The city of Valdivia received the most damage as a result of this record-breaking earthquake, although other cities throughout Chile also suffered severe damage. The total impact area was recorded within a 150,000-square mile area, which stretched from the town of Talca to the Chiloe Island. Regions located above tectonic depressions seemed to be hardest hit. One example of this is Puerto Octay, located within the Central Valley, which received the strongest tremors of any city not within of the Valdivia Basin.
Impact of the Most Powerful Earthquake on Humans
The number of deaths caused by the Valdivia Earthquake is estimated to lie somewhere between 4,000 and 6,000 individuals. Houses were destroyed throughout the affected area with most of the damage located at lower elevations, where the earthquake vibrations were the strongest. In Valdivia alone, at least 40% of the houses fell to the ground, which caused approximately 20,000 people to be homeless. Some infrastructure was also damaged and one bridge was lost completely in this city.
Outside of urban areas, agricultural areas suffered from both the earthquake and the resulting floods. These natural disasters worked together to take the lives of people and livestock. The recently developed economy in the town of Queule was also destroyed as it had previously relied on fishing and agriculture for survival.
Impact of the Most Powerful Earthquake on Nature
In addition to the loss of homes, economic opportunities, and human lives, the Great Chilean Earthquake resulted in significant environmental damage as well. As previously mentioned, tsunami waves ripped across the ocean and crashed against shorelines around the world. In Chile, these strong waves destroyed ports and caused several boats to wreck.
Some researchers believe this earthquake may have also triggered a volcano eruption. Less than 2 days after the event, the Cordón Caulle volcano erupted. The eruption created several vents, which emitted lava and ash over a time period of nearly a month. Luckily, this event did not cause damage to any local community.
The earthquake shook through the mountains located further inland as well. This violent movement shook rocks and soil loose from the tops of mountains, resulting in landslides throughout the affected area. These landslides were primarily concentrated along the Liquiñe-Ofqui fault line in the southern region of the Andes mountain range. In some cases, the falling earth destroyed the surrounding vegetation and rural roadways. In general, however, no communities were harmed by these landslides.
One of the most serious consequences of the earthquake-induced landslides occurred when the exit of the Riñihue Lake was blocked. With the outflow blocked, the lake was unable to drain its excess water supply into the San Pedro River. The water in the lake was held back by a relatively low, 78-foot tall dam. As the water level began rising, fed by the Enco river, authorities worked to evacuate the area. Additionally, local officials began excavating the area to make room for more water. Eventually, they built dams around upper-level lakes to prevent water from flowing into the Riñihue Lake and built dykes around the lake itself in order to contain the water.
In total, experts estimate that the total monetary damage caused by this earthquake was equal to between $3.24 and $6.48 billion, adjusted for inflation.